Insulin resistance is a condition of having diminished response to normal amounts of circulating insulin thus resulting in high insulin release from the pancreas. This condition is associated with hypertension. The relative influences of high insulin levels and high blood pressure on size and function of blood vessels in patients with longstanding hypertension. This is a substudy of a larger trial designed to evaluate the effect of 2 antihypertensive agents, Losartan (an angiotensin receptor blocker) versus Atenolol (a beta blocker), on left ventricular hypertrophy (thickening of the heart muscle wall). The substudy will evaluate the effect of these two agents on glucose uptake (sugar metabolism), insulin levels, and carotid blood vessel wall thickness.